This invention relates to a perhydrofluorene derivative, a process for producing the same and fluid for traction drive which contains the same. More particularly, it relates to a perhydrofluorene drivative suitable as a fluid used for traction driving devices such as automatic transmission device in automobiles, variable-speed transmission devices of machines, etc., a process for efficiently producing said derivative by a simple operation and fluid for traction drive which make it possible to make traction driving devices smaller and lighter.
Recently, miniaturization and lightening of traction driving devices by using fluid have been studied especially in the field of automboiles. Thus, development of traction driving fluids having high performances in a wide temperature range has been demanded.
That is, it is desired for fluid for traction drive that even if viscosity thereof increases at low temperatures, they can be practically used in a temperature range where they are normally used, for example, -30.degree. C.-140.degree. C. and further retain high traction coefficients at high temperatures and have high heat stability and oxidation stability.
Hitherto, for example, a perhydrofluorene compound represented by the following general formula: ##STR3## (wherein R represents a cyclohexyl group, an ethyl group or a lauryl group) has been proposed as traction driving fluid. [cf. Japanese Patent Publication (Kokoku) No. 338/71 corresponding to U.S. Pat. No. 3,411,369].
However, this perhydrofluorene compound is low in traction coefficient and so, contacting area of fluid and mechanical part must be increased when this compound is used as a traction driving fluid and this is disadvantageous for miniaturization of traction driving devices.